1. Field of the Invention
The present invention relates generally to a roll forming machine, and more particularly, is directed to an improved mechanism for wrapping twine or the like around a roll of crop material formed within the roll forming machine.
2. Description of the Prior Art
In recent years, the practice of harvesting crop material such as hay or the like by forming it into large rolls through the use of large roll or round balers has become increasingly popular. One type of large round baler forms a swath or windrow of hay into a large cylindrical roll or round bale while the latter is supported on the ground. Another type of large round baler picks up the swath or windrow of hay and forms it into a large round bale off the ground. Both of these types of large round balers generally have mechanism for applying or wrapping twine or similar binding material about the bale once it has reached its desired maximum size. The twine is then severed and the wrapped bale is discharged from the machine.
One type of a twine wrapping mechanism associated with such large round balers is seen in U.S. Pat. No. 3,910,178 wherein there is shown an elongated tube which oscillates to dispense twine across the bale forming region of the machine. As the dispensing tube is returned to its rest condition, the twine is drawn over a cutting knife to sever the twine extending from the end of the tube. Such severing operation requires that the twine be in a tight or taut condition because a loosely held twine could not be severed under such conditions. Furthermore, once the twine is severed, the free or tail end of the twine is uncontrolled and may slip back within the dispensing tube or may become entangled with various components of the machine, thus, hampering the wrapping operation of the next bale.
Another type of twine wrapping mechanism associated with the large round balers is found in U.S. Pat. No. 3,913,473. Shown is a hydraulic cylinder that drives a twine dispensing tube back and forth across the bale forming region wherein the twine is wrapped about the bale. As the dispensing tube returns to its rest condition it actuates a twine cut-off mechanism wherein an anvil swings upwardly, engaging the twine and moving the same against a knife to sever the twine extending from the end of the tube. After severence, the free end of the twine remains clamped between the knife and the anvil. Should the hydraulic cylinder or hydraulic lines leak, the dispensing tube would creep away from its rest position and could be damaged or cause damage to other components of the round baler. Furthermore, the anvil would slip away from an abutting engagement with the knife, releasing the free end of the twine which would cause potential problems in the wrapping operation of the next bale.